The present disclosure herein relates to an X-ray generator, and more particularly, to a field electron emission type X-ray generator and a driving method for stably driving the same.
In order to generate an X-ray, a manner is used in which an electron emitted in a vacuum tube is accelerated and the accelerated electron is struck to an anode electrode. As the manner for emitting the electron, a thermal electron emission type and a field electron emission type are largely used, As a typical X-ray tube, the thermal electron emission type is used the most, which heats a filament in a vacuum glass tube. Recently, researches are being actively performed on an electric field emission type X-ray tube for which a digital control is easy.
A commercialized thermal electron emission type X-ray generator uses a current source for providing a current flowing through a tungsten filament that is an electron emission source. Unlike this, a field electron mission type X-ray generator emits an electron by applying a high voltage to a metal tip or a carbon nano tube. The field electron emission type X-ray generator (or tube) is driven by grounding a cathode electrode and applying a positive voltage to gate and anode electrodes.
However, for the field electron emission type X-ray generator applied to non-destruction inspection equipment, it is necessary that a target is externally exposed or heat generated at the anode electrode is effectively removed. In this case, it is necessary to connect the anode electrode to a ground and apply a negative voltage to the gate and cathode electrodes. In order to drive the X-ray generator in such a way, it is necessary to generate a negative high voltage and a voltage higher than the negative high voltage by a prescribed level. Accordingly, there is a limitation that it is very difficult to realize a method for driving the field electron emission type X-ray generator of which the anode electrode is grounded in consideration of insulation and stability.